Duncan is better.He won 4 titles without All-NBA teammate.He controlled every aspect of the game.

7 straight games during the 03 WCSF and 03 WCF

G4 03 WCSF 36/9/5

G5 03 WCSF 27/14/5

G6 03 WCSF 37/16/4/2

G1 03 WCF 40/15/7/1

G2 03 WCF 32/15/5/3

G3 03 WCF 34/24/6/6

G4 03 WCF 21/20/7/4

G1 03 Finals 32/20/6/7

G3 03 Finals 21/16/7/3

G5 03 Finals 29/17/4/4

G6 03 Finals 21/20/10/8

Keep in mind that Duncan's production skyrockets against the NBA's elite.He outscores consistently his peers in the postseason.Duncan outscored Shaq in (1999,2002,2003,2008),Dirk in (2001,2003,2006,2009),Amare (2003,2007,2008) or Garnett (2001)